Ice storm frequencies in a warmer climate

Ice storms can produce extensive damage to physical infrastructure, cause deaths and injuries, and result in large losses through business interruption. Total costs can be billions of dollars. If society is to increase its resilience to such events, we need a better understanding of the likely frequency, intensity and geographical distribution of ice storms. Unfortunately, due to competing temperature and precipitation effects as well as surface effects, it is unclear how climate change will affect the frequency, intensity and geographical distribution of ice storms. Here we perform a simple “thought experiment” using vertical temperature profile data to explore how these might change given plausible future temperature regimes. As temperatures increase, we find a poleward shift and a shift toward winter. Furthermore, southern locations experience fewer ice storms at all times of the year, while northern areas experience fewer in the spring and fall and more in the winter. Using an approximation for surface effects, we estimate that a temperature increase will result in an increased frequency of ice storm events throughout much of the winter across eastern Canada and in the U.S. west of the Appalachian Mountains as far south as Tennessee. Future changes in variability may enhance or moderate these changes.